For most of the curved shapes, i use thin styrene as the skin and styrene rods as the scaffold. Once the glue has dried, i put milliput putty around the scaffold to reinforce. It takes time to build it up this way but the result is very stable and firm.

Things are a bit messy right now. I am working on the cockpit but there are quite a few things missing still. The view from the back show the scaffold and milliputt resin. I have been drilling through the resin to thread optical fibers through.

I have been using 100 meters as the length. At 1/144 scale, my model length is about 80 cm. There is a reddit discussion about whether the hammerhead corvette is 100 or 300 meters in length. The reddit conclusion is for 100 meters. That is consistent with what we see on screen. Views from the cockpit and views of the cockpit from exterior help establish the length.